After bottling fermented homebrew (and taking ample samples to ensure the
quality of the fermentation :-)) ), shake up the slurry from the almost
empty SECONDARY fermentor and bottle (fill 1/3 of bottle) in 3-4 bottles. Put
in fridge until ready to use. i make sure the bottles are clean (dishwasher)
and that's it!!
i use Glosch-type bottles, and when i need yeast for my next batch, i
simply open bottle and pour half into starter (or even into wort) and it
works (:^)) !!

Of course i have never really done a second passage reuse (i.e. resuse
the slurry from this second generatoin of yeast), but it should be ok!!

The yeast have stayed in the fridge as long as 4-6 months before use,
and they start up happily and ferment very smoothly.